Recovery of goat·damaged vegetation in an insular tropical montane forest

Abstract

The feral goat (Capra hircus) is an alien herbivore that has wreaked havoc in island ecosystems, including the dry, rugged, and relatively inaccessible montane koa parkland on the islands of Maui and Hawai'i. The objective of the present work was to evaluate the ability of koa parkland on Maui to recover naturally from browsing damage if goats are eliminated. We studied recovery over 7 years by periodically determining percent ground cover, species composition, and woody plant abundance inside and outside a goat exclosure. Initially, plant cover did not differ inside and outside the exclosure; but, after 3 years, plant cover inside was almost twice that outside. Molassesgrass (Melinis minutijlora), an introduced mat-forming species, spread rapidly inside the exclosure and showed no sign of dying out or retreating. Goats exert some control over this species. After 7 years, tree regeneration has occurred only inside the exclosure except for koa (Acacia koa) regeneration, which also occurred outside the exclosute. Heights of koa seedlings indicated that those outside represented recent germinants only, while those inside represented older individuals as well as recent germinants. The results indicated that the aging koa overstory could be replaced by koa regeneration if goats were eliminated and that some native species (Dodonaea, Styphelia, Coprosma) could at least partially recover. Once established, some introduced species (e.g., Melinis minutijlora), are favored by elimination of goats and may severely inhibit recovery of native species

Citation

Scowcroft, Paul G.; Hobdy, Robert. 1987. Recovery of goat·damaged vegetation in an insular tropical montane forest. Biotropica 19(3): 208-215